The Directory in an Oracle9i Real Application Clusters Environment, 4 of 6

Oracle Directory Server Connection Modes to Real Application Clusters Database Instances

This section discusses the various connection modes possible for Oracle directory server instances communicating with Oracle9i Real Application Clusters database instances. These connection modes are transparent to the Oracle Internet Directory clients, and do not affect the way in which Oracle Internet Directory communicates with its clients.

This section contains these topics:

Load_balance

If the load_balance parameter in the tnsnames.ora file is set to on, then Oracle Internet Directory connections to the Oracle9i Database Server is distributed to each Oracle9i Database Server node. During failover of any node, only connections to the failed node are redirected to the available Oracle9i Database Server nodes.

If the load_balance parameter is set to off, then all the Oracle Internet Directory connections to the Oracle9i Database Server are to one Oracle9i Database Server node only.

During failover, all the connections are redirected to the available Oracle9i Database Server nodes.

Connect-Time Failover (CTF)

At the time of connection to the Oracle9i Database Server by the Oracle directory servers, if the primary Oracle9i Database Server node is not available, then Oracle Internet Directory servers connect to the backup--that is, secondary--database.

Transparent Application Failover (TAF)

To configure TAF, in the tnsnames.ora file, add type=select and method=preconnect.

During any LDAP search operation, if the primary Oracle9i Database Server node fails, then the Oracle directory server transparently connects to the backup--that is, the secondary--Oracle9i Database Servere node, and the current LDAP search operation continues.

Configuring the tnsnames.ora File for the Failover

This section shows configurations of the tnsnames.ora files on two nodes.

Node 1

db.us.acme.com= 
 (description=  
  (load_balance=off/on)  /* only connect time load balancing & connection load 
balancing */
  (failover=on)          /* only connect time failover */
  (address=  
       (protocol=tcp)  
       (host=db1)  
       (port=1521)) 
 (address=  
       (protocol=tcp)  
       (host=db2)  
       (port=1521)) 
  (connect_data= 
     (service_name=db.us.acme.com) 
     (failover_mode=
       (backup=db2.acme.com)
       (type=select) 
       (method=preconnect))))

db2.acme.com= 
 (description=  
  (address=  
       (protocol=tcp)  
       (host=db2)  
       (port=1521)) 
  (connect_data= 
     (service_name=db.us.acme.com) 
     (instance_name=db2)
     (failover_mode=
     (backup=db2.acme.com)
     (type=select)
     (method=preconnect))
     ))

Node 2

db.us.acme.com= 
 (description=  
  (load_balance=off/on)  /* only connect time load balancing & connection load 
balancing */
  (failover=on)          /* only connect time failover */
  (address=  
       (protocol=tcp)  
       (host=db2)  
       (port=1521)) 
 (address=  
       (protocol=tcp)  
       (host=db1)  
       (port=1521)) 
  (connect_data= 
     (service_name=db.us.acme.com) 
     (failover_mode=
       (backup=db1.acme.com)
       (type=select) 
       (method=preconnect))))

db1.acme.com= 
 (description=  
  (address=  
       (protocol=tcp)  
       (host=db1)  
       (port=1521)) 
  (connect_data= 
     (service_name=db.us.acme.com) 
     (instance_name=db2)
     (failover_mode=
     (backup=db2.acme.com)
     (type=select)
     (method=preconnect))))